1. Nanotechnology and aptamers: applications in drug delivery
Etgar Levy-Nissenbaum, Aleksandar F. Radovic-Moreno, Andrew Z. Wang, Robert Langer, Omid C. Farokhzad 
Trends in Biotechnology 
Volume 26, Issue 8, Pages (August 2008)
DOI: /j.tibtech
Copyright © 2008 Elsevier Ltd Terms and Conditions

2. Figure 1
Example of a SELEX protocol used to develop aptamers against live cells. (a) A pool of 2′F-Py RNAs was incubated with suspended parental PC12 cells in a set of counter-selection steps (b,c). The counter-selection steps served to eliminate oligonucleotides with affinity for motifs that are present on non-targeted cells, as well as those with affinity for other epitopes present in the tissue culture system, including the flasks and materials. (c) Unbound sequences yielded from the first counter-selection step are recovered by centrifugation and incubated with adherent PC12/MEN2B cells in a second counter-selection step. (d) Resulting unbound sequences in the supernatant were recovered and incubated with adherent PC12/MEN2A for the selection step. (e) Unbound sequences were discarded by several washing steps. (f) Bound sequences were recovered by phenol extraction. (g) Sequences enriched by the selection step were amplified by RT–PCR and in vitro transcription before a new cycle of selection was imitated. Adapted, with permission, from Ref. [17].
Trends in Biotechnology  , DOI: ( /j.tibtech )
Copyright © 2008 Elsevier Ltd Terms and Conditions

3. Figure 2
Nanoparticle–aptamer conjugate formation and cell-specific uptake. (a) Illustration of a nanoparticle that contains a fluorescent dye (in red) that is decorated on the surface with polymers containing terminal carboxyl groups. The amine-modification to the RNA aptamer molecule can be used to form nanoparticle–aptamer conjugates using carbodiimide chemistry. (b) Fluorescent nanoparticles (encapsulating rhodamine-labeled dextran) that are linked to RNA aptamers specific for the PSMA (NP–apt) were internalized into PSMA-expressing LNCaP cells (PSMA+) but not PSMA-non-expressing PC3 cells (PSMA−) after incubation for 16h. The nucleus is stained in blue [4′,6-diamidino-2-phenylindole (DAPI)] and the cytoskeleton in green (adapted, with permission, from Ref. [35]). Abbreviations: Apt, aptamer; NP, nanoparticle.
Trends in Biotechnology  , DOI: ( /j.tibtech )
Copyright © 2008 Elsevier Ltd Terms and Conditions